Lowering your Volkswagen
First option and the most economical approach to aftermarket suspension. Lowering springs will generally range from $150-300 , and will lower the car a set or static amount. Lowering springs will help you reduce your vehicles ride height, can offer improvement in ride quality, and will also help to improvement handling through more ideal spring rates for aggresive driving.
Coilovers offer the ultimate in spring based performance and adjustment/customization. Coilovers will allow the user to set a wide range of ride heights. This is accomplished by threaded shock bodies with adjustable locking collars that sit under the spring. Often the rear of the car is adjusted via a perch that sits under the rear springs, as the shocks and springs are separate on many modern cars. In addition coilovers can also allow adjustable dampening, rebound, and camber. Most commonly a combination of rebound and dampening adjustment is offered, and is adjusted via the strut mount in the front or rear of the car. Coilovers can even offer lower ride heights while maintaining full spring travel for a smooth ride by offering adjustable shock bodies.
Air ride allows the user to adjust their ride height on the fly, as well as offering extreme lowering capabilities. Unlike factory air ride, aftermarket air ride adjusts quickly and offers wider ranges of ride heights. This is accomplished by replacing standard coil springs with heavy duty rubber bellows that inflate and deflate to raise or lower the vehicle. Air ride, while mainly associated with visual tuning, can still provide a sportier ride comparable to coilovers. Air ride installs are much more complicated, requiring air tank(s), compressor(s), air lines, air management systems, water traps, and level sensors to all be wired and installed in order to have a complete and functioning system.
Whenever you're lowering your vehicle it is recommended that you get an alignment done once the vehicle has settled in. Getting an alignment will help prevent premature tire wear caused by a vehicle going out of spec during the lowering process.